A. Field of the Invention
This invention relates generally to capacitor discharge ignition systems and more particularly to ignition control arrangements to achieve desired timing characteristics and engine control.
B. Description of the Prior Art
Various capacitor discharge ignition systems of the prior art have been developed to provide a breakerless ignition system for the control of an engine whereby an appropriately timed signal is supplied to the primary winding of an ignition coil to induce a high voltage in a secondary winding of the ignition coil to fire a spark plug or spark plugs associated with the engine. Examples of these various capacitor discharge ignition systems are disclosed in U.S. Pat. Nos. 4,228,780, 4,202,305, 3,941,111, 4,056,088 and 4,036,201.
Additionally, various capacitor discharge ignition systems of the prior art have been developed to provide predetermined ignition timing characteristics. These prior art arrangements are directed to achieving predetermined ignition timing characteristics including both advancing and retarding of the ignition signal for predetermined operating parameters of the engine as well as achieving a stable ignition timing characteristic over predetermined operating ranges of an engine.
For example, the aforementioned U.S. Pat. No. 4,202,305 discloses an arrangement for providing a stable ignition timing characteristic over a wide operating range of engine speed. Further, the aforementioned U.S. Pat. No. 4,228,780 discloses an arrangement for providing a predetermined ignition timing retard characteristic with increasing engine speed operation.
Other timing control arrangements of the prior art to achieve various predetermined timing characteristics are disclosed in U.S. Pat. Nos. 4,074,669, 3,667,441, 3,703,889, 4,132,208, 3,941,110, 3,722,488, 4,108,131, 4,029,998, 3,515,109, 3,447,521, 3,500,809 and 3,465,739.
These prior art arrangements are directed to various techniques for the control of engine timing characteristics including: the generation of various pulses in accordance with the shape of the rotating magnet pole shoes; a plurality of magnets arranged around a flywheel for the generation of various additional timing pulses; the change in trigger voltage obtained as a variation of engine speed; two or more coils for developing trigger pulses; and various electronic trigger control circuits operating in combination with the variation in pulses obtained in the capacitor discharge ignition system as a function of engine speed.
For example, U.S. Pat. No. 4,132,208 is directed to a provision of electronic control circuits including a phase advanced signal generating circuit with phase angle control and an angle retarding circuit for the controlled timing.
Further U.S. Pat. No. 3,941,110 is directed to the provision in various embodiments of control circuits including RC components, zener diodes and multivibrator stages that are responsive to control timing in response to the change in trigger waveforms as a function of engine speed.
Further, various other prior art arrangements are disclosed that propose a variety of mechanical and electrical arrangements to relatively abruptly alter timing characteristics either as a retard or an advance in response to sensed engine RPM or induced voltages reflecting engine RPM as disclosed in U.S. Pat. Nos. 4,174,697, 4,252,095, 4,335,692, 4,306,535, 4,195,603, 3,752,139, 4,140,092, 4,282,839, 3,320,770, 4,154,201, 3,703,887, 3,626,455, 3,874,350, 4,099,498 and 3,653,367.
For example, U.S. Pat. No. 4,174,697 is directed to an electrical circuit arrangement in a magneto generator for introducing an abrupt advance in ignition timing. At a predetermined speed, the time between the breakdown of a threshold element and the furnishing of the signal which causes interuption of the primary current is decreased. The time is shortened either by decreasing the time constant of the timing circuit connected to the threshold element, or by switching a second timing circuit into the circuit having a shorter time constant.
U.S. Pat. No. 4,252,095 utilizes an RPM sensing circuit output to switch control from one timing control circuit to another retard timing control circuit to introduce an ignition retard above a predetermined speed.
U.S. Pat. No. 4,335,692 is directed to a circuit arrangement for introducing a relatively abrupt retard in ignition timing at a predetermined engine RPM that increases with increasing RPM. A pick-up coil and rectifier-limiter circuit, separate from the charge coil, provide a variable trigger signal to the CID system.
While these prior art arrangements are generally suitable for their intended purpose to provide engine timing control, it is desirable to provide improved timing control circuits and capacitor discharge ignition systems.